The invention relates to functionalized 1,3-butadiene polymers and copolymers, and to specific processes for making functionalized conjugated diene polymers.
The production of hydroxyl and carbonyl compounds by reacting olefins with carbon monoxide and hydrogen is known. The products contain, as a rule, one more carbon atom than the reacting olefin. The reaction requires a hydrocarbon-soluble catalyst, usually one containing cobalt, iron, nickel or rhodium atoms, i.e., metals selected from Group 8 of the Periodic Table of the Elements, in complex bond with at least one ligand consisting of a carbon monoxide molecule and often a second ligand containing an organic compound of an atom, such as phosphorus or arsenic, selected from Group 5a of the Periodic Table.
U.S. Pat. No. 3,776,981 and equivalent British patent specification No. 1,378,185 describe a process for preparing a hydroxylated block copolymer by reacting, with carbon monoxide and hydrogen, an unsaturated block copolymer having at least one polymer block of a monoalkenylarene and at least one polymer block of a conjugated diene wherein the polymer block of the conjugated diene has a 1,2 or 3,4 microstructure content of between 0% and 30% and a 1,4 microstructure content of between 100% and 70%, the reaction with carbon monoxide and hydrogen being continued until substantially all of the unsaturation of the conjugated diene block(s) is removed, 10-100% thereof being replaced by hydroxymethyl groups and 90-0% thereof being replaced by hydrogen atoms. This known process may be carried out as a one-step process, but then relatively high hydrogen pressures are required.
European Patent Application Publication No. 148592 describes the preparation of carboxylic acid or ester derivatives of polymeric compounds containing residual unsaturation. The polymers are reacted with carbon monoxide and an alcohol in the presence of a protonic acid, a Group 8 metal or Group 8 metal compound, and a copper compound. The application presents data for functionalization of polyisobutylene which has a single unsaturated carbon-carbon bond per molecule. The functionalization of other unsaturated polymers by the same process is suggested although not specifically described.
U.S. Pat. No. 3,539,654 describes the modification of styrenic block copolymers with carbon monoxide and an acid in the presence a metal halide catalyst. The resulting polymer was reported to have a significant gel content and to contain ester and aldehyde functionality before treatment with alcohol potash and with copper ions and water. This patent also describes the non-catalysed reaction of a random structured polybutadiene with carbon monoxide in water followed by reaction with ethanol resulting in a polymer that reportedly contains ether bonds or carboxylate groups.
Conversion of conjugated diene monomers into a polydiene block occurs in several ways using the lithium based catalysts, preferably lithium alkyls, employed according to the prior art. Polymerization of butadiene leads to a mixture of several types of polymer microstructures, known as cis-1,4, trans-1,4 and 1,2 microstructures. In the cis-1,4 and trans-1,4 structures, carbon arrangement is all in a line and no small side chains are formed; thus, the double bonds produced are internal in the backbone chain. In the 1,2 microstructure, a two-carbon vinyl group is present as a short side chain directly attached to the two remaining carbon atoms of the original diene monomer unit. All three types of microstructure may be present in a polydiene block, but process conditions are known in the art to maximize or minimize any of the three types of microstructures if so desired.
A fourth type of microstructure known as 3,4 microstructure is also formed when substituted conjugated diolefins are polymerized. This is the case when isoprene is used.